From mboxrd@z Thu Jan 1 00:00:00 1970 From: Raymond Yau Subject: Re: wrong decibel data? Date: Thu, 8 Apr 2010 10:05:28 +0800 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-pw0-f51.google.com (mail-pw0-f51.google.com [209.85.160.51]) by alsa0.perex.cz (Postfix) with ESMTP id 1AFBF1038F1 for ; Thu, 8 Apr 2010 04:05:29 +0200 (CEST) Received: by pwj8 with SMTP id 8so572085pwj.38 for ; Wed, 07 Apr 2010 19:05:29 -0700 (PDT) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: ALSA Development Mailing List List-Id: alsa-devel@alsa-project.org 2010/4/6 Nicolo' Chieffo > I've already attached my alsa-info.log in my first post. > > > > * alsamixer 0 dB (100%): > Simple mixer control 'Master',0 > Capabilities: pvolume pswitch pswitch-joined penum > Playback channels: Front Left - Front Right > Limits: Playback 0 - 65536 > Mono: > Front Left: Playback 64044 [98%] [on] > Front Right: Playback 64044 [98%] [on] > Most users only care about 0dB point since any software gain is the cause of clipping (distortion) when the volume control provide software gain http://en.wikipedia.org/wiki/Clipping_%28audio%29 In digital signal processing, clipping occurs when the signal is restricted by the range of a chosen representation. For example in a system using 16-bit signedintegers, 32767 is the largest positive value that can be represented, and if during processing the amplitude of the signal is doubled, samplevalues of 32000 should become 64000, but instead they are truncated to the maximum, 32767.